switch to special casing 0-value

src/main-thread/commands/storage.ts

@@ -2,7 +2,7 @@ import { CommandExecutorInterface } from './interface';
 import { TransferrableMutationType, StorageMutationIndex } from '../../transfer/TransferrableMutation';
 import { StorageLocation } from '../../transfer/TransferrableStorage';
 import { TransferrableKeys } from '../../transfer/TransferrableKeys';
-import { MessageType, StorageValueToWorker, GetOrSet, DELETION_INDEX } from '../../transfer/Messages';
+import { MessageType, StorageValueToWorker, GetOrSet } from '../../transfer/Messages';
 
 export const StorageProcessor: CommandExecutorInterface = (strings, nodeContext, workerContext, objectContext, config) => {
   const allowedExecution = config.executorsAllowed.includes(TransferrableMutationType.STORAGE);
@@ -64,8 +64,8 @@ export const StorageProcessor: CommandExecutorInterface = (strings, nodeContext,
 
         // TODO(choumx): Clean up key/value strings (or don't store them in the first place)
         // to avoid leaking memory.
-        const key = keyIndex != DELETION_INDEX && keyIndex >= 0 ? strings.get(keyIndex) : '';
-        const value = valueIndex != DELETION_INDEX && valueIndex >= 0 ? strings.get(valueIndex) : null;
+        const key = keyIndex > 0 ? strings.get(keyIndex) : '';
+        const value = valueIndex > 0 ? strings.get(valueIndex) : null;
 
         if (operation === GetOrSet.GET) {
           get(location, key);
@@ -82,8 +82,8 @@ export const StorageProcessor: CommandExecutorInterface = (strings, nodeContext,
       const keyIndex = mutations[startPosition + StorageMutationIndex.Key];
       const valueIndex = mutations[startPosition + StorageMutationIndex.Value];
 
-      const key = keyIndex >= 0 ? strings.get(keyIndex) : null;
-      const value = valueIndex >= 0 ? strings.get(valueIndex) : null;
+      const key = keyIndex > 0 ? strings.get(keyIndex) : null;
+      const value = valueIndex > 0 ? strings.get(valueIndex) : null;
 
       return {
         type: 'STORAGE',

src/main-thread/strings.ts

@@ -5,7 +5,11 @@ export class StringContext {
   private strings: Array<string>;
 
   constructor() {
-    this.strings = [];
+    this.strings = [
+      // The 0th index is reserved for meaning no value. Or delete.
+      // For example, the storage.removeItem code path.
+      null as any,
+    ];
   }
 
   /**

src/test/Emitter.ts

@@ -15,7 +15,10 @@ export interface Emitter {
  * mutation transfer state is also stored at the module-level.
  * TODO: Remove this and replace with strings.getForTesting() at call sites.
  */
-const strings: Array<string> = [];
+const strings: Array<string> = [
+  // First index reserved to signify deletion.
+  null as unknown as string,
+];
 
 /**
  * Stubs `document.postMessage` to invoke callbacks passed to `once()`.

src/test/main-thread/commands/function.test.ts

@@ -29,7 +29,7 @@ test('Returns the value of a resolved function', async (t) => {
   const mutations: number[] = [];
   mutations[FunctionMutationIndex.Status] = ResolveOrReject.RESOLVE;
   mutations[FunctionMutationIndex.Index] = index;
-  mutations[FunctionMutationIndex.Value] = 0;
+  mutations[FunctionMutationIndex.Value] = 1;
 
   processor.execute(new Uint16Array(mutations), 0, true);
   t.deepEqual(await promise, { val: true });
@@ -41,7 +41,7 @@ test('Is able to return undefined', async (t) => {
   const mutations: number[] = [];
   mutations[FunctionMutationIndex.Status] = ResolveOrReject.RESOLVE;
   mutations[FunctionMutationIndex.Index] = index;
-  mutations[FunctionMutationIndex.Value] = 0;
+  mutations[FunctionMutationIndex.Value] = 1;
 
   processor.execute(new Uint16Array(mutations), 0, true);
   t.deepEqual(await promise, undefined);
@@ -53,7 +53,7 @@ test('Returns the value of a rejected value', (t) => {
   const mutations: number[] = [];
   mutations[FunctionMutationIndex.Status] = ResolveOrReject.REJECT;
   mutations[FunctionMutationIndex.Index] = index;
-  mutations[FunctionMutationIndex.Value] = 0;
+  mutations[FunctionMutationIndex.Value] = 1;
 
   processor.execute(new Uint16Array(mutations), 0, true);
   return promise.then(

src/test/main-thread/commands/storage.test.ts

@@ -56,7 +56,7 @@ test('StorageProcessor sends storage value event to worker', async (t) => {
   const mutation: number[] = [];
   mutation[StorageMutationIndex.Operation] = GetOrSet.GET;
   mutation[StorageMutationIndex.Location] = StorageLocation.AmpState;
-  mutation[StorageMutationIndex.Key] = 0;
+  mutation[StorageMutationIndex.Key] = 1;
   const mutations = new Uint16Array(mutation);
 
   processor.execute(mutations, 0, true);
@@ -77,8 +77,8 @@ test('StorageProcessor handles deletion event from worker', async (t) => {
   const mutation: number[] = [];
   mutation[StorageMutationIndex.Operation] = GetOrSet.SET;
   mutation[StorageMutationIndex.Location] = StorageLocation.Local;
-  mutation[StorageMutationIndex.Key] = 1;
-  mutation[StorageMutationIndex.Value] = -1;
+  mutation[StorageMutationIndex.Key] = 2;
+  mutation[StorageMutationIndex.Value] = 0;
   const mutations = new Uint16Array(mutation);
 
   processor.execute(mutations, 0, true);

src/test/main-thread/deserializeTransferrableObject.test.ts

@@ -157,7 +157,7 @@ test('Returns the correct end offset', (t) => {
 
 // main-thread's strings API does not return an ID when storing a string
 // so for convenience:
-function storeString(stringContext: StringContext, text: string, currentIndex = -1) {
+function storeString(stringContext: StringContext, text: string, currentIndex = 0) {
   stringContext.store(text);
   return ++currentIndex;
 }

src/test/main-thread/mutator.test.ts

@@ -70,9 +70,9 @@ test.serial('batch mutations', (t) => {
     new Uint16Array([
       TransferrableMutationType.ATTRIBUTES,
       2, // Base Node
+      1,
       0,
-      0,
-      0 + 1,
+      1 + 1,
     ]),
   );
   mutator.mutate(
@@ -82,9 +82,9 @@ test.serial('batch mutations', (t) => {
     new Uint16Array([
       TransferrableMutationType.ATTRIBUTES,
       2, // Base Node
-      1,
+      2,
       0,
-      1 + 1,
+      2 + 1,
     ]),
   );
 
@@ -102,9 +102,9 @@ test.serial('batch mutations', (t) => {
     new Uint16Array([
       TransferrableMutationType.ATTRIBUTES,
       2, // Base Node
-      2,
+      3,
       0,
-      2 + 1,
+      3 + 1,
     ]),
   );
 
@@ -140,9 +140,9 @@ test.serial('batch mutations with custom pump', (t) => {
     new Uint16Array([
       TransferrableMutationType.ATTRIBUTES,
       2, // Base Node
+      1,
       0,
-      0,
-      0 + 1,
+      1 + 1,
     ]),
   );
   mutator.mutate(
@@ -152,9 +152,9 @@ test.serial('batch mutations with custom pump', (t) => {
     new Uint16Array([
       TransferrableMutationType.ATTRIBUTES,
       2, // Base Node
-      1,
+      2,
       0,
-      1 + 1,
+      2 + 1,
     ]),
   );
 
@@ -174,9 +174,9 @@ test.serial('batch mutations with custom pump', (t) => {
     new Uint16Array([
       TransferrableMutationType.ATTRIBUTES,
       2, // Base Node
-      2,
+      3,
       0,
-      2 + 1,
+      3 + 1,
     ]),
   );
 
@@ -209,9 +209,9 @@ test.serial('leverage allowlist to exclude mutation type', (t) => {
     new Uint16Array([
       TransferrableMutationType.ATTRIBUTES,
       2, // Base Node
+      1,
       0,
-      0,
-      0 + 1,
+      1 + 1,
     ]),
   );
   mutator.mutate(
@@ -221,9 +221,9 @@ test.serial('leverage allowlist to exclude mutation type', (t) => {
     new Uint16Array([
       TransferrableMutationType.ATTRIBUTES,
       2, // Base Node
-      1,
+      2,
       0,
-      1 + 1,
+      2 + 1,
     ]),
   );
 
@@ -257,9 +257,9 @@ test.serial('split strings from mutations', (t) => {
     new Uint16Array([
       TransferrableMutationType.ATTRIBUTES,
       2, // Base Node
+      1,
       0,
-      0,
-      0 + 1,
+      1 + 1,
     ]),
   );
 

src/test/main-thread/object-creation.test.ts

@@ -197,7 +197,7 @@ test('Returns correct end offset', (t) => {
   t.is(mutationsArray[endOffset], 32);
 });
 
-function storeString(stringContext: StringContext, text: string, currentIndex = -1) {
+function storeString(stringContext: StringContext, text: string, currentIndex = 0) {
   stringContext.store(text);
   return ++currentIndex;
 }

src/test/main-thread/object-mutation.test.ts

@@ -321,7 +321,7 @@ function executeCall(
 
 // main-thread's strings API does not return an ID when storing a string
 // so for convenience:
-function storeString(stringContext: StringContext, text: string, currentIndex = -1) {
+function storeString(stringContext: StringContext, text: string, currentIndex = 0) {
   stringContext.store(text);
   return ++currentIndex;
 }

src/test/main-thread/string-properties.test.ts

@@ -101,7 +101,7 @@ test('setting property back to an empty string', (t) => {
   t.is(inputElement.value, secondUpdateValue);
 });
 
-function storeString(stringContext: StringContext, text: string, currentIndex = -1) {
+function storeString(stringContext: StringContext, text: string, currentIndex = 0) {
   stringContext.store(text);
   return ++currentIndex;
 }

src/test/mutation-transfer/storage.test.ts

@@ -1,6 +1,6 @@
 import anyTest, { TestInterface } from 'ava';
 import { Document } from '../../worker-thread/dom/Document';
-import { DELETION_INDEX, GetOrSet } from '../../transfer/Messages';
+import { GetOrSet } from '../../transfer/Messages';
 import { Storage, createStorage } from '../../worker-thread/Storage';
 import { StorageLocation } from '../../transfer/TransferrableStorage';
 import { TransferrableMutationType } from '../../transfer/TransferrableMutation';
@@ -54,7 +54,7 @@ test.serial.cb('Storage.removeItem', (t) => {
   const { document, storage } = t.context;
 
   expectMutations(document, (mutations) => {
-    t.deepEqual(mutations, [TransferrableMutationType.STORAGE, GetOrSet.SET, StorageLocation.Local, getForTesting('foo'), DELETION_INDEX]);
+    t.deepEqual(mutations, [TransferrableMutationType.STORAGE, GetOrSet.SET, StorageLocation.Local, getForTesting('foo'), 0]);
     t.end();
   });
 
@@ -65,7 +65,7 @@ test.serial.cb('Storage.clear', (t) => {
   const { document, storage } = t.context;
 
   expectMutations(document, (mutations) => {
-    t.deepEqual(mutations, [TransferrableMutationType.STORAGE, GetOrSet.SET, StorageLocation.Local, DELETION_INDEX, DELETION_INDEX]);
+    t.deepEqual(mutations, [TransferrableMutationType.STORAGE, GetOrSet.SET, StorageLocation.Local, 0, 0]);
     t.end();
   });
 

src/transfer/Messages.ts

@@ -107,7 +107,3 @@ export const enum ResolveOrReject {
   RESOLVE = 1,
   REJECT = 2,
 }
-
-// Mutations are are modeled as Uint16Array.
-// Deletion is specified as a -1, which when placed into the array becomes 2^16-1.
-export const DELETION_INDEX = 2 ** 16 - 1;

src/worker-thread/Storage.ts

@@ -1,5 +1,5 @@
 import { Document } from './dom/Document';
-import { DELETION_INDEX, GetOrSet } from '../transfer/Messages';
+import { GetOrSet } from '../transfer/Messages';
 import { StorageLocation } from '../transfer/TransferrableStorage';
 import { TransferrableMutationType } from '../transfer/TransferrableMutation';
 import { store } from './strings';
@@ -58,7 +58,13 @@ export function createStorage(document: Document | DocumentStub, location: Stora
     value(key: string): void {
       delete this[key];
 
-      transfer(document, [TransferrableMutationType.STORAGE, GetOrSet.SET, location, store(key), DELETION_INDEX]);
+      transfer(document, [
+        TransferrableMutationType.STORAGE,
+        GetOrSet.SET,
+        location,
+        store(key),
+        0, // value == 0 represents deletion.
+      ]);
     },
   });
   define(storage, 'clear', {
@@ -67,7 +73,13 @@ export function createStorage(document: Document | DocumentStub, location: Stora
         delete this[key];
       });
 
-      transfer(document, [TransferrableMutationType.STORAGE, GetOrSet.SET, location, DELETION_INDEX, DELETION_INDEX]);
+      transfer(document, [
+        TransferrableMutationType.STORAGE,
+        GetOrSet.SET,
+        location,
+        0, // key == 0 represents all keys.
+        0, // value == 0 represents deletion.
+      ]);
     },
   });
   return storage as Storage;

src/worker-thread/strings.ts

@@ -1,4 +1,4 @@
-let count: number = 0;
+let count: number = 1; // count starts from 1 since 0th index is reserved to mean "no value" or "delete".
 let transfer: Array<string> = [];
 const mapping: Map<string, number> = new Map();